The following references are relevant prior art for the subject matter of the present invention:
1. Barnett C. P., Donati E. J., Gath L. (1984), Differences between adult and neonatal rats in their astroglial response to spinal injury, Exp. Neurol 84:374-385.
2. Wolman L. (1967), Post-traumatic regeneration of nerve fibers in the human spinal cord and its relation to intramedulatory neuroma. J.Path.Bact. 94:123-129.
3. Young J. S., Northup N. E. (1979), Statistical information pertaining to some of the most asked questions about spinal cord injury. Sci Digest 1:11.
4. De La Torre J. C. (1981), Spinal cord injury. Review of basic and applied research. Spine 6:315-335.
5. Collins W. F. (1983), A review and update of experimental and clinical studies of spinal cord injury. Paraplegia 21:204-219.
6. Aguayo A. J., Benfey M. and David S. (1983), A potential for axonal regeneration in neurons of the adult mammalia nervous system. Birth Defects: Original Article Series 19:327-340.
7. David S. and Aguayo A. J. (1985), Axonal regeneration after crush injury of rat central nervous system fibres innervating peripheral nerve grafts; J. Neurocytol 14:12.
8. Rochkind S. (1978), Stimulation effect of laser energy on the regeneration of traumatically injured peripheral nerves. The Krim National Medical Inst., Morphogenesis and Regenerations 73:48-50.
9. Nissan M., Rochkind S., Razon N. and Bartal A. (1986), HeNe laser irradiation delivered transcutoneously: its effect on sciatic nerve of rats. Laser. Surg. Med. 6:435-438.
10. Rochkind S., Nissan M., Razon N., Schwarts M. and Bartal A. (1986), Electrophysiological effect of HeNe laser on normal and injured sciatic nerve in the rat. Acta Neurochir (Wien) 83:125-130.
11. Richardson P. N., McGuinness U. M., Aguayo A. I. (1980), Axons from CNS neurons regenerate into PNS graft. Nature 1980; 284:264-265.
12. Wrathall J., Rigamonti D. D., Bradford M. R., Kao C. C. (1982), Reconstruction of the contused cat spinal cord by the delayed nerve graft technique and cultured peripheral non-neuronal cells. Acta Neuropathol (Berl) 57:59-69.
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14. Richardson P. M., Issa V. M. K. (1984), Peripheral injury enhances central regeneration of primary sensor neurons. Nature 309:791-792.
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Nerve fibres in the central nervous system of mammals in general, and humans in particular, are incapable of spontaneous complete regeneration after injury and consequently any paraplegia resulting from spinal cord injury is permanent. The inability of the spinal cord to regenerate is attributed mainly to large cicatrices which are formed by the glial scar present at the site of injury (Ref. 1 and 2).
Peripheral nerve fibres, on the other hand, do regenerate in many cases, thereby restoring motor and sensory functions. However their regeneration, apart from not always being complete, progresses at a rather slow rate.
Spinal cord injuries are among the major clinical problems encountered in neurological and neurosurgical wards (Ref. 3). Therefore, it has been the object of extensive research throughout the world to find methods for inducing the restoration of motor functions paralysed upon injury of the spinal cord, so far, however, to no avail (Ref. 4 and 5). Thus, while it was demonstrated in rats whose spinal cords were experimentally transected that nerve fibres can grow through an autologous peripheral nerve graft transplanted into the site of injury, such growth did not bring about the desired restoration of motor functions (Ref. 6 and 7).
It has already been suggested that the regeneration of injured peripheral nerves can be accelerated by low energy laser irradiation applied to the injured nerve (Ref. 8). Thus, Rochkind et al. (Ref. 9, 10) demonstrated that trancutaneous low energy laser irradiation of the sciatic nerve induced an increase in the amplitude of the electrical signals recorded in the irradiated nerve, i.e. increasing the size of the action potential.